In the history of the automotive industry, few things have been quite as unexpected as the rise of the S.U.V. Detroit is a town of engineers, and engineers like to believe that there is some connection between the success of a vehicle and its technical merits. But the S.U.V. boom was like Apple's bringing back the Macintosh, dressing it up in colorful plastic, and suddenly creating a new market. It made no sense to them.